Polyacetal polymers, which are commonly referred to as polyoxymethylene polymers, have become established as exceptionally useful engineering materials in a variety of applications. Polyoxymethylene polymers, for instance, are widely used in constructing molded parts, such as parts for use in the automotive industry and the electrical industry. Polyoxymethylene polymers have excellent mechanical properties, fatigue resistance, abrasion resistance, and chemical resistance.
Although polyoxymethylene polymers have excellent physical characteristics, the polymers may not be suitable components in certain applications, such as in fuel transfer applications, where the risk of a spark or explosion is increased. Because the electrical resistances within plastics such as polyoxymethylene are usually very high, there is a risk of electrostatic charging, which can be disruptive and even dangerous in certain application sectors, such as in the fuel and automotive sectors. This risk is due to the inability of the polymers to dissipate electrical charge. For instance, unlike metallic components, which provide an electrical pathway for electrical charges to move freely to ground, when a non-conductive, plastic component is used, such a pathway is removed, leaving no way for charges to drain to ground. This, in turn, creates a risk of sparking or explosion when a plastic component is used. As such, fillers including metal fibers such as stainless steel fibers or electro-conductive (EC) carbon black can be added to polyoxymethylene to impart the polyoxymethylene with electrostatic dissipative (ESD) capabilities. However, problems exist in the laser welding of such polyoxymethylenes having ESD capabilities because these polyoxymethylenes do not absorb laser energy sufficiently to form a high quality weld interface. This can be problematic in the construction of certain articles such as filter housings, flanges, pressure vessel connectors, fuel line connectors, or other parts that require both electrical conductivity and laser weldability.
In view of the above, a need exists for a laser-weldable polyoxymethylene polymer composition that also has electrostatic dissipative (ESD) capabilities and articles formed from such a composition.